Geodorum densiflorum

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Geodorum densiflorumFamily: Orchidaceae
Genus: Geodorum
Synonym: G. neocaledonicum, G. pictum
Common name(s): Pink Nodding Orchid, Shepherd’s Crook Orchid
ALA reference

I was amazed to discover this orchid growing under trees in a very exposed position in the picnic ground. It has obviously been growing there for a long time – I can’t imagine how we missed seeing it in previous years. Although I haven’t previously seen this species in the Reserve, it was included on our list of native plants, having been recorded by Paul Grimshaw when he did a brief survey of the site over 10 years ago. The small pink flowers remain cupped and do not open fully.

Orchids, like lilies, have three sepals and three petals however with orchids the third petal is modified to form the labellum. Almost all orchid flowers open with the labellum lowermost to act as a landing pad for the pollinator, which is usually an insect. Orchid flower buds as they start to develop on the flower spike have the labellum uppermost. In order to open with the labellum lowermost, most orchid flowers twist the ovary through 180° as the bud develops but before the flower opens. This orchid achieves the desired result of having the labellum lowermost in a rather unique way. It turns the top of the flower spike through 180° so that it hangs down like a shepherd’s crook. Now there is no need for the ovary to rotate and the photo below clearly shows that no rotation of the ovary has occurred. Once the flowers have been pollinated the seed pods start to develop and the flower spike straightens up. (February 2014)

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